1. Field of the Invention
The present invention relates to a power supplying device, power supply controlling method, power supply controlling program, and network system and more particularly to the power supplying device, the power supply controlling method, the power supply controlling program, and the network system being suitably applied to a PoE (Power over Ethernet®)-ready switch/router and the like to feed power through Ethernet to a plurality of communication terminals to transmit or receive data in a form of a packet.
2. Description of the Related Art
A PoE-ready switch/router to feed power to a plurality of communication terminals to transmit or receive data in a form of a packet through the Ethernet is configured to supply power, if a PoE function is set to be in an ON state, unless a user intentionally sets the PoE function to be an in OFF state and, therefore, a problem arises that a constant amount of power is consumed irrespective of a use status of a network. To solve this problem, a power supplying device that can reduce power consumption of an entire network is proposed.
The power supplying device of this type is disclosed in Patent Reference 1 (Japanese Patent Application Laid-open No. 2006-085503). According to the power supplying device, whether or not the communication terminal in which part or all of the connecting terminals are connected to a connector serving as a power supplying terminal is in a non-power requiring state is judged based on time data and a time period representing and non-power feeding time period, or based on a relation between the detection of frequency requiring power supply and time threshold. Then, the power supply is stopped to the communication terminal using the corresponding connector. This is attributable to reduce unnecessary power supply. Moreover, the communication state is measured based on power consumption of each communication terminal.
However, the above technology disclosed in the Patent Reference has the following problems. That is, in the above conventional PoE-ready switch/router, the ON/OFF state for the PoE function is set by manipulation of the user, however, it is actually difficult to make settings of the ON/OFF state of the PoE function based on a use state of the PoE power receiving device. A problem arises that no dynamic control is made according to actual use state of the PoE power receiving device, as a result, allowing power to be fed even to the PoE power receiving device not in use, thus causing power to be consumed wastefully.
Also, in the power supplying device disclosed in the Patent Reference 1, the power control is performed for every port of each communication terminal, however, the communication state is judged based on power consumption of each communication terminal and, therefore, the content of the technology disclosed in the Patent Reference 1 is different from that of the present invention. Moreover, in the power supplying device disclosed in the Patent Reference 1, mounting of a measuring circuit to measure power at each port is required and, therefore, some measure has to be taken in the case where an amount of power consumption of a device to be targeted varies in terms of hardware. In this case, for example, a complicated process such as settings of a threshold value for power consumption for each device is made necessary.